code: def test_simple_tagger_can_enable_span_f1(self):
      assert (
          self.model.calculate_span_f1
          and self.model._f1_metric is not None
      )
  
imports: from flaky import flaky
  import numpy
  import pytest
  import torch
  from allennlp.common.testing import ModelTestCase
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.params import Params
  from allennlp.data.dataset_readers import DatasetReader
  from allennlp.data.data_loaders import DataLoader, SimpleDataLoader
  from allennlp.models import Model
  from allennlp.training import GradientDescentTrainer, Trainer
label_desc: Use image node_id 4 for calling the SimpleTaggerSpanF1Test obj's underlying member method code with example usage: obj.test_simple_tagger_can_enable_span_f1() without return types